Are gravity modes found in –Scuti stars?

Scuti stars are pulsators situated in the classical instability strip on the main sequence or moving from the main sequence to the giant branch. Some Scuti stars are radial pulsators, while the majority show small-amplitude nonradial pressure (p) modes. For the more evolved stars, many these p modes may actually be modes of mixed p/g character. A number of Scuti stars show periods which are too long for p (or radial) modes. Some of these periods have been interpreted as gravity (g) modes. This raises the question whether these stars could be both Scuti and Doradus variables.
We examine the observational evidence for these long periods and conclude that they are not observational artifacts. We then test alternate explanations for the long periods. These explanations include rotational effects on the luminosity (i.e., mean density) calibrations, combination frequencies (f –f ), rotation periods and forced oscillations from a binary companion.

 
Print this abstract